Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/28—Materials for coating prostheses
  • A61L27/34—Macromolecular materials
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
  • A61L29/08—Materials for coatings
  • A61L29/085—Macromolecular materials

Definitions

• the present invention relates generally to methods of making fluid-tight, implantable, inflatable silicone reservoirs such as those used in making tissue expanders, mammary prostheses, or balloon catheters.
• Subcutaneous tissue expanders have come into wide use because of the variety of plastic surgical procedures that have been developed which either require that tissue be expanded to receive an implant or that a flap of tissue be generated for use on some other part of the body.
• tissue expanders One method of making tissue expanders involves coating a mandrel with a fluid elastomeric composition, curing the composition, and, subsequently, removing the cured composition from the mandrel.
• An envelope made by this method usually has folds when in its deflated state. Although this method produces very satisfactory envelopes, a flat tissue expander envelope which is generally without folds is sometimes desired.
• a second way of making tissue expander envelopes is by sealing two layers of vulcanized elastomer together by placing a washer of raw elastomer between them and curing the washer while in pressure contact with the two layers of vulcanized elastomer.
• tissue expander envelope is described in EP 0 196,821, as a one-piece molded body within which is a free-floating member of Teflon or other like non-stick fluorocarbon material of a slightly smaller geometrical shape similar to that of the top and bottom silicone layers of the one piece molded body.
• the non-stick member acts as a valve, keeps the tube linking the injection port and the expander free and clear of silicon during the molding process, and provides for non-sticking surfaces during expansion.
• U.S. Patent No. 4,100,627 to Brill discloses a gel filled flexible article comprising a flexible container containing silicone gel prepared from methylphenylvinyl­siloxy-endblocked polydimethylsiloxane.
• U.S. Patent Nos. 4,455,691 and 4,472,226 to Redinger et al. disclose an implantable prosthesis comprising a flexible sac and a silicone gel contained with the sac.
• the wall of the sac is comprised of at least one continuous layer of silicone elastomer which substantially impedes the migration of the silicone gel from the sac.
• the silicone elastomer which impedes the migration is disclosed as preferably being a reaction product of dimethylpolysiloxane and either 3,3,3-trifluoropropylpolysiloxane, diphenylpolysiloxane or methylphenylpolysiloxane.
• Canadian Patent No. 1,199,451 to Larson teaches of a rubber article comprising a flexible silicone rubber container filled with a silicone gel composition, there being an essentially continuous barrier layer of a composition consisting essentially of a fluorine-­containing organopolysiloxane situated between the interior of the container and the gel.
• Certain fluorosilicon-containing materials are known as release materials for coating a substrate for releasing silicone pressure sensitive adhesives (hereinafter referred to as SPSAs), e.g., as in Keil, U.S. Patent No. 3,050,411, and Olson, U.S. Patent No. 4,472,480.
• SPSAs silicone pressure sensitive adhesives
• U.S. Patent No. 4,565,714 to Koshar discloses a low energy release liner for SPSAs comprising the hydrosilylation reaction product of an ethylenically unsaturated perfluoropolyether and a compound bearing silicon-bonded hydrogen atoms.
• U.S. Patent No. 4,039,707 to O'Malley teaches of a SPSA comprising the intercondensation product of a mixture containing an organopolysiloxane resin and an alkylarylpolysiloxane gum and a releasable layer comprising a cured reactive terminal group containing dimethylpolysiloxane fluid-coated sheet on the SPSA.
• U.S. Patent No. 4,465,805 to Blizzard et al. discloses curable fluorosilicone coatings which are suitable for coating substrates, such as silicone rubber, and are suitable for use in making release paper.
• 3,544,668 to Dereniuk discloses a way of keeping the balloon and tube separated by applying a coating of a gel, e.g. methylcellulose, between the balloon and the tube which is later decomposed by drying.
• U.S. Patent No. 3,528,869, also to Dereniuk discloses coating the portion of the shaft that is to be covered by the balloon with a release agent, such as Baymal or Silica.
• U.S. Patent Nos. 3,926,705 and 3,983,879 to Todd disclose a catheter having an outer covering, a portion of which is inflatable to form a bubble, and a layer of thermoplastic material applied around the catheter in the region underlying the bubble wherein the themoplastic layer is composed of a material to which the outer covering does not adhere. Todd discloses that when the catheter is silicone, suitable materials for the themoplastic layer are polyethylene or polypropylene tape.
• U.S. Patent No. 4,536,179 to Anderson et al. discloses a catheter having a silicone tube and a silicone sleeve in face-to-face contact which are provided with a thin film coating of a glow discharge plasma polymerized fluorocarbon between them to prevent adhesion of the contacting surfaces.
• U.S. Patent No. 4,413,359 to Akiyama discloses sandwiching a fluororubber (e.g. vinylidene fluoride-­hexafluoropropylene-based fluororubber) membrane between two silicone rubber layers to form a laminate membrane.
• a fluororubber e.g. vinylidene fluoride-­hexafluoropropylene-based fluororubber
• Japanese Patent application OPI 149962/84 discloses a releasable masking composition prepared by dispersing tetrafluoro­ethylene telomer in organic solvents.
• the composition is said to have no adherence to paint.
• Simultaneous use of silicon type water repellent or fluorine type water and oil repellent, mold release agent or surfactant e.g., dimethylpolysiloxane, polyfluoroalkyl group containing (meth)acrylate copolymer
• mold release agent or surfactant e.g., dimethylpolysiloxane, polyfluoroalkyl group containing (meth)acrylate copolymer
• the invention disclosed herein provides a method for making an implantable, inflatable reservoir comprising the steps of a) coating a section of a surface of a first at least partially uncured silicone elastomer layer with a masking material selected from the group consisting of silicone materials which are not readily compatible with the silicone elastomer, such as, a non-curable fluorosilicone composition or a curable fluorosilicone mixture, leaving a perimeter around the section which is substantially free of said masking material, b) placing a surface of a second at least partially uncured silicone elastomer layer in contact with said surface of said first layer so that said second layer contacts substantially the entire length of said perimeter, and c) curing said coated first layer and said second layer while in contact, thereby sealing the layers at the perimeter and providing a reservoir between said layers enclosed by said sealed perimeter and having the shape of said coated section.
• the method can optionally have the additional step of curing the coated masking material after step (a) and before step (b).
• the method is especially suitable for making a low-profile implantable envelope useful for tissue expansion or a mammary prosthesis or for making the balloon portion of a catheter.
• the invention provides a method for making an implantable silicone reservoir by applying masking material between two layers of silicone elastomer in the area where adhesion is undesirable leaving a perimeter free of the masking material, then, subsequently curing the two layers of silicone elastomer together at their perimeter whereby the layers remain non-adhered in the coated area.
• silicone elastomer Several types are suitable for the invention as long as the silicone elastomers are uncured ("raw") or only partially cured when the masking material is applied.
• the uncuring masking material more types of elastomer systems are usable, since there is no concern of inactivating the cure of the masking material and less danger of interfering with the cure of the elastomer system.
• condensation curable compositions containing siloxanes having ⁇ SiOH radicals and crosslinkers having ⁇ SiOR radicals could be used with the non-curable masking material discussed below.
• silicone elastomers which cure by ⁇ SiH to CH2CHSi ⁇ addition be used.
• the thickness, size, and shape of the elastomer layers will vary with the desired resulting reservoir.
• the masking material is a silicone material which is generally non-compatible with the silicone elastomer used.
• the masking material can be, for example, a non-curable fluorosilicone composition, a curable fluorosilicone composition or the masking material can be a phenylsiloxane composition.
• the silicone material is a curable fluorosilicone composition or a non-curable fluorosilicone composition, and most preferably, the silicone material is a non-curable fluorosilicone composition.
• Suitable fluorosilicone compositions comprise a fluorosilicone polymer containing at least 2 mol percent, based on the total number of siloxane units in the fluorosilicone polymer, of fluorinated siloxane units, any remaining siloxane units in the polymer being non-fluorinated siloxane units; said fluorinated siloxane units having the formula (RQ)(R′) a (Z) b SiO (3-a-b)/2 and said non-fluorinated siloxane units having the formula (R′) c (Z) d SiO (4-c-d)/2 ⁇ where, in said fluorinated and non-fluorinated siloxane units, R denotes a perfluoroalkyl radical having less than 9 carbon atoms, Q denotes
• Suitable curable fluorosilicone compositions comprise a curable mixture consisting essentially of (A) the fluorosilicone polymer described immediately above where the polymer also contains an average of at least two silicone-­bonded curing radicals per molecule and (B) an effective amount of a curing agent for the fluorosilicone polymer.
• the fluorosilicone polymer (Component A) described above is an organopolysiloxane consisting essentially of fluorinated siloxane units, optionally, non-fluorinated siloxane units, and, optionally for the non-curable compositions, but required for the curable compositions, silicon-bonded curing radicals.
• the silicon-bonded curing radicals are selected from the group consisting of hydrogen atoms, hydroxyl radicals and alkenyl radicals, examples of the latter being vinyl, allyl, butenyl, pentenyl, hexenyl, octenyl and decenyl.
• the aliphatic unsaturation in the alkenyl curing radicals is in the terminal, l.e. omega position.
• fluorinated siloxane units siloxane polymer units that bear a perfluoroalkyl radical suitably bonded to a silicon atom.
• the fluorinated siloxane units have the formula (RQ)(R′) a (Z) b SiO (3-a-b)/2 , general examples of which include chain-terminating siloxane units having the formula (RQ)(R′) a (Z) b SiO l/2 , where the sum of a+b is 2, such as (RQ)(R′)2SiO 1/2 , (RQ)(Z)2SiO 1/2 and (RQ)(R′)(Z)SiO 1/2 , chain-extending siloxane units having the formulae (RQ)(R′)SiO 2/2 and (RQ)(Z)SiO 2/2 and chain-branching siloxane units having the formula (RQ)SiO 3/2 .
• the non-fluorinated siloxane units if present, have the formula (R′) c (Z) d SiO (4-c-d)/2 , general examples of which include chain-terminating siloxane units having the formula (R′) c (Z) d SiO l/2 where the sum of c+d is 3, such as (R′)3SiO 1/2 , (R′)2(Z)SiO 1/2 , (R′)(Z)2SiO 1/2 and (Z)3SiO 1/2 , chain-extending siloxane units having the above formula where the sum of c+d is 2, such as (R′)2SiO 2/2 , (R′)(Z)SiO 2/2 and (Z)2SiO 2/2 and chain-branching siloxane units having the above formula where the sum of c+d is 1 or 0, such as (R′)SiO 3/2 , (Z)SiO 3/2 and SiO 4/2 .
• the fluorosilicone polymer can have any viscosity up to several million centistokes, it is believed necessary that the polymer not be a non-fluid, such as a gel or a solid. Therefore, said chain-branching siloxane units, if present, should be present in only minor amounts.
• the fluorosilicone polymer be made up of only chain-extending and chain-terminating siloxane units selected from the group consisting of YMe2SiO 1/2 , RQMeYSiO 1/2 , MeYSiO 2/2 and RQYSiO 2/2 siloxane units; wherein Y denotes Me or A, A denotes an omega-alkenyl radical and Me denotes the methyl radical.
• Y denotes Me or A
• A denotes an omega-alkenyl radical
• Me denotes the methyl radical.
• siloxane units include, but are not limited to, Me3SiO 1/2 , Me2ViSiO 1/2 , RQMe2SiO 1/2 , RQMeViSiO 1/2 , Me2SiO 2/2 , MeViSiO 2/2 , RQMeSiO 2/2 and RQViSiO 2/2 , where R is, for example, perfluorobutyl.
• fluorosilicone polymers include, but are not limited to, the following: YMe2SiO(MeYSiO) m (RQYSiO) n SiMe2Y, RQMeYSiO(MeYSiO) m (RQYSiO) n SiMeYRQ, Me3SiO(Me2SiO) 0.95m (MeViSiO) 0.05m (RQMeSiO) n SiMe3, ViMe2SiO(Me2SiO) m (RQMeSiO) n SiMe2Vi, ViMeRQSiO(RQMeSiO) n SiMeRQVi, Me2RQSiO(RQMeSiO) 0.95n (RQViSiO) 0.05n and Me3SiO(Me2SiO) m (RQMeSiO) 0.90
• the fluorosilicone polymer have a linear structure and be represented by the formula YMe2SiO(Me2SiO) x [RCH2CH2Si(Me)O] y (MeASiO) z SiMe2Y wherein the values of x and y are each greater than zero, and x, y, and z are such that the fluorosilicone polymer contains at least 5 mol percent fluorinated siloxane units.
• the fluorosilicone polymer additionally have in-the-chain curing radicals where z is greater than 0 and x, y, and z are such that the fluorosilicone polymer contains from 1 to 10 mol percent alkenyl-containing siloxane units and the balance dimethylsiloxane units and the curing agent comprises a mixture of a platinum-containing hydrosilylation catalyst and a methylhydrogenpolysiloxane having the formula Me3SiO(MeHSiO) e SiMe3 wherein e has a value of from 30 to 70.
• compositions wherein the fluorosilicone polymer has a linear structure as represented by the formula noted immediately above wherein the values of x and y are each greater than zero and are such that the fluorosilicone polymer contains from 20 to 50 mol percent fluorinated siloxane units and has a viscosity of from 100 to 1000 centistokes at 25°C.
• compositions are those where z is greater than 0 and x, y, and z are such that the fluorosilicone polymer contains from 3 to 7 mol percent vinyl-containing siloxane units and the balance dimethylsiloxane units and the curing agent comprises a platinum-containing hydrosilylation catalyst and a methylhydrogenpolysiloxane having the formula Me3SiO(MeHSiO) e SiMe3 wherein e has a value of from 30 to 70.
• the terminal Y radicals can be methyl or alkenyl, such as vinyl, without significantly altering the masking ability. However, for curable compositions it may be desirable that the terminal Y radicals be alkenyl under moderate curing conditions, such as low curing temperatures, short curing times or attenuated curing catalyst activity.
• R denotes a perfluoroalkyl radical having from less than 9 carbon atoms, over the complete range of from 2 to 100 mol% fluorinated siloxane units.
• the R radicals can be identical or different and can have a normal or a branched structure.
• Examples thereof include CF3-, C2F5-, C3F7-, C4F9-, such as CF3CF2 CF2CF2-, (CF3)2CFCF2-, (CF3)3C- and CF3CF2(CF3)CF-; C5F11-, such as CF3CF2CF2CF2-; C6F13-, such as CF3(CF2)4CF2-; C7F14-, such as CF3(CF2CF2)3-; and C8F17-.
• R is a perfluoroalkyl radical having from 4 to 8 carbons atoms and the fluorosilicone polymer contains from 2 to 100 mol percent fluorinated siloxane units, or R is a perfluoroalkyl radical having from 2 to 3 carbons atoms when the fluorosilicone polymer contains less than 90 mol percent fluorinated siloxane units, or R is a perfluoroalkyl radical having 1 carbon atom when the fluoro­silicone polymer contains from 7 to 10 mol percent fluorinated siloxane units.
• R can be C9F19-, C10F21-, and larger.
• polymers containing perfluoroalkyl radicals containing 1 to 8 carbon atoms provide excellent results and that the use of larger perfluoroalkyl radicals would only provide incremental improvements at higher cost.
• Each perfluoroalkyl radical is bonded to a silicon atom by way of Q, a divalent spacing radical containing carbon, hydrogen and, optionally, oxygen and/or sulfur atoms which are present as ether and thioether linkages, respectively.
• the sulfur and oxygen atoms, if present, must be bonded to only carbon atoms.
• Each Q radical can have any structure containing the elements listed; however, each is preferably an alkylene radical having a normal or branched structure.
• suitable alkylene radicals include -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH2-, -(CH2CH2)2-, -CH2(CH3)CH2CH2- and -CH(CH3)CH2-.
• Each fluorinated radical, RQ preferably has the formula RCH2CH2-.
• the fluorosilicone polymers preferably contain fluorinated siloxane units delineated above whose RQ radicals have the structure CF3CF2CF2CF2Q-, and most preferably CF3CF2CF2CF2CH2CH2-.
• R′ denotes a silicon-bonded monovalent hydrocarbon radical, preferably having from 1 to 6 carbon atoms, and containing no aliphatic unsaturation.
• the R′ radicals can be identical or different, as desired.
• suitable R′ radicals include alkyl radicals, such as methyl, ethyl, propyl, isopropyl, butyl, hexyl, 2-ethyl-­hexyl, octyl, isooctyl and decyl; aryl, such as phenyl, tolyl, benzyl, beta-phenylethyl and styryl.
• aryl such as phenyl, tolyl, benzyl, beta-phenylethyl and styryl.
• Z denotes a silicon-bonded curing radical selected from the group consisting of hydrogen, hydroxyl and alkenyl, as delineated above.
• m, n, x, y and z for the linear fluorosilicone polymer denote average values, as is well known in the art, and are such that the polymer contains the requisite amount of alkenyl-containing siloxane units in the case of curable compositions and fluorinated siloxane units and has the desired viscosity at 25°C.
• the values of m, n, m+n, x, y, z and x+y+z thus will vary greatly, depending on the fluorinated siloxane unit content, the structure of the fluorinated radicals and the viscosity of the polymer.
• the values of x and y can be as small as one and the value of z can be as small as 0, the values of x and y can range to 10,000 and more and the value of z typically is zero or limited to a fraction, such as from 1/100 to 2/10, of the sum of x+y+z.
• Suitable curing agents, Component (B), for Component (A) comprise a crosslinking agent, examples of which include, but are not limited to, aliphatically unsaturated compounds to react with silicon-bonded hydrogen curing radicals, and organohydrogen silicon compounds bearing a plurality of silicon-bonded hydrogen atoms to react with silicon-bonded alkenyl curing radicals and/or silicon-bonded hydroxy curing radicals.
• the curing agent typically comprises a curing catalyst to accelerate the reaction of the curing radicals with the crosslinking agent, particularly at elevated temperature.
• aliphatically unsaturated cross linking agents include organosilicon compounds such as silanes and cyclic, linear and resinous siloxanes which bear a plurality of silicon-bonded alkenyl radicals.
• organohydrogen silicon cross linking agents include any organosilicon compound which bears a plurality of silicon-bonded hydrogen atoms, such as cyclic, linear and resinous siloxanes, such as methylhydrogencyclo­polysiloxanes having the unit formula MeHSiO 2/2 ; linear methylhydrogenpolysiloxanes having the formulae Me3SiO(MeHSiO) i (Me2SiO) j SiMe3 and HMe2SiO(MeHSiO) i (Me2SiO) j SiMe2H where i and j have values of zero or more; branched siloxanes such as (HMe2SiO)4Si and the fluorosilicone crosslinkers disclosed by Holbrook in U.S.
• Suitable, well known curing catalysts include, but are not limited to, organoperoxides, platinum-­group metals and their compounds, and tin and lead salts of carboxylic acids, such as stannous octoate and dibutyltin diacetate.
• the curable compositions usable in this invention preferably comprise a curing agent which comprises a platinum-containing hydrosilylation catalyst and a methyl­hydrogenpolysiloxane having the formula Me3SiO(MeHSiO) e SiMe3 wherein e has a value of from 30 to 70.
• a particularly useful platinum-containing catalyst for the curable compositions is the chloroplatinic acid-vinylsiloxane complex disclosed by Willing in U.S. Patent No. 3,419,593.
• the platinum-containing catalyst can be any of the well known materials that are effective for catalyzing the hydro­silylation reaction of silicon-bonded hydrogen atoms with silicon-bonded vinyl radicals.
• the amount of curing agent to be used in the curable compositions is not normally critical, it only being necessary to have an effective amount thereof to cure the composition to the desired amount.
• an effective amount of a curing agent will contain a sufficient amount of crosslinking agent to provide one or more crosslinking radicals for every curing radical in the fluorosilicone polymer.
• the curing agent comprises a methylhydrogen­polysiloxane
• it is preferred that a sufficient amount thereof would provide from 1 to 10, preferably from 1 to 4, silicon-bonded hydrogen atoms for every curing radical in the fluorosilicone polymer.
• a curing catalyst in the curable compositions to provide a rapid cure rate.
• the exact amount of said catalyst will depend on the particular catalyst that is used and is not easily predicted. However, for chloroplatinic acid and its complexes, an amount sufficient to provide from 10 to 500 parts by weight of platinum for every one million parts by weight of the fluorosilicone polymer is usually sufficient. Within this range, routine experimentation can be used to determine the optimum amount of catalyst needed for any particular cure time.
• compositions can further comprise various amounts of optional components that will not adversely limit the use of the composition as a masking material for silicone elastomers.
• optional components include reactive components, such as catalyst activity attenuators to inhibit the activity of the catalyst, if used, at room temperature and unreactive components such as diluents to decrease the viscosity of the composition.
• Preferred diluents include halogenated solvents, such as chlorofluorocarbons; esters, such as ethyl acetate; ketones such as methylisobutyl ketone; and ethers, such as dibutyl ether.
• Preferred catalyst activity attenuators include methylvinylcyclosiloxanes; esters of unsaturated alcohols and/or unsaturated acids, such as diallyl maleate and bis(2-methoxyisopropyl) maleate; acetylenic compounds, such as methylbutynol; and eneynes, such as ethynylcyclo­hexene.
• the reader is referred to, for example, the disclosures of U.S-. Patent Nos. 3,445,420; 4,256,870; 4,465,818 and 4,562,096, to further illustrate the optional attenuator component of the compositions.
• curable fluorosilicone materials rather than non-curable fluorosilicone compositions in the invention.
• curable fluorosilicone materials when it is desired to minimize the amount of flow of the material on the elastomer before curing the elastomer, it may be preferred to cure the masking material in place.
• curable fluorosilicone materials when curable fluorosilicone materials are used as the masking material and the envelope is to be filled with a silicone gel, the envelope may have the additional advantage of being more "bleed resistant", i.e. more resistant to migration of silicone gel through the envelope wall.
• non-curable fluorosilicone compositions were found to be preferable to the curable compositions.
• the curable materials have the potential for premature gellation, and, for this reason alone, it may be more desirable to use non-curable fluorosilicone materials as the masking material.
• the fluorosilicone polymers can be prepared by any of several methods disclosed in the art.
• the hydroxy-terminated polymers can be prepared by the method of Johannson, U.S. Patent No. 3,002,951 or Brown, U.S. Patent No. 3,179,619.
• the organo-terminated polymers can be prepared by the method of Pierce et al., U.S. Patent No. 2,961,425.
• the fluorosilicone polymers may be prepared using the preferred method as disclosed in copending U.S. Serial No. 870,567, filed on June 4, 1986, and stated generally below.
• the vinyl-containing copolymers of the general formula YMe2SiO(Me2SiO) x [RCH2CH2Si(Me)O] y (MeASiO) z SiMe2Y, wherein the values of x, y and z are each greater than zero, are preferably prepared by the method as disclosed as the preferred method in copending U.S. patent application Serial No. 870,567.
• step (I) a cohydrolyzate of a mixture of fluorinated and non-fluorinated silanes is first prepared which has greater compatibility with polydimethylsiloxanes than does the hydrolyzate of the fluorinated silanes alone. It has been found that cohydrolyzates having as much as 90 percent fluorinated siloxane units have this improved compatibility with polydimethylsiloxanes. However, it is desirable to incorporate as much non-fluorinated silane into the hydrolyzate as possible, based on the composition of the polymer to be prepared and the compatibility of the silanes.
• fluorosilicone polymers which contain up to 50 mol percent fluorinated siloxane units
• the silanes that are mixed and cohydrolyzed in (I) bear at least one hydrolyzable radical (X) per molecule.
• hydrolyzable radicals are preferably chlorine atoms, it is believed that they can also be any other halogen atom, an alkoxy radical such as methoxy-or ethoxy, an acyloxy radical such as acetoxy or an amino radical such as NH2 or NH.
• suitable fluorinated silanes include RQMeYSiX and RQYSiX2, such as RQ(Me)SiCl2, RQ(Vi)SiCl2, RQ(Me)22SiCl and RQ(Me)(Vi)SiCl.
• non-fluorinated siloxane units examples include YMe2SiX and MeYSiX2, such as Me2SiCl2, MeViSiCl2, Vi(Me)2SiCl and Me3SiCl.
• the silanes are preferably dissolved in a water-­insoluble solvent such as a dialkylether and the resulting solution added to water with vigorous agitation. If halosilanes are not used, it is preferred that the water be made acidic with a mineral acid such as hydrochloric acid.
• the resulting hydrolyzate is then freed of any solvent and mixed with an organopolysiloxane having the formula R ⁇ h SiO (4-h)/2 , examples of which include cyclic siloxanes having the formulae (Me2SiO) i and (MeASiO) i , wherein i has a value of at least 3, such as [(Me)2SiO]3 ⁇ 10 and [(Me)(Vi)SiO]3 ⁇ 10; and linear siloxanes having the formula YMe2SiO(Me2SiO) j (MeViSiO) k SiMe2Y, wherein j and k have values of zero or more, such as Me3SiO(Me2SiO)0 ⁇ 10(MeViSiO)0 ⁇ 10SiMe3 and ViMe22SiO(Me2SiO)0 ⁇ 10(MeViSiO)0 ⁇ 10SiMe
• the mixture of hydrolyzate and organopolysiloxane is brought into contact with a siloxane-equilibrating catalyst such as an acidic catalyst such as sulfuric acid-­treated clays or ion-exchange resins, fluoroalkanesulfonic acids, perfluoroalkanesulfonic acids or mineral acids such as hydrochloric acid or sulfuric acid; or a basic catalyst such as alkali metal hydroxides, alkali metal silanolates or tetraalkyl ammonium or phosphonium hydroxides or silanolates.
• a siloxane-equilibrating catalyst such as an acidic catalyst such as sulfuric acid-­treated clays or ion-exchange resins, fluoroalkanesulfonic acids, perfluoroalkanesulfonic acids or mineral acids such as hydrochloric acid or sulfuric acid; or a basic catalyst such as alkali metal hydroxides, alkali metal silanolates
• the catalyst is preferably deactivated, such as by neutralization; although this step is not necessary. It is also desirable, but not necessary, to remove volatile materials from the fluorosilicone polymer before it is used for this invention.
• the masking materials can be applied to the elastomer surface in a solvent free state or as a dispersion.
• the silicones be applied in dispersion so that the viscosity is low enough to apply a substantially uniform layer by the desired technique but not so low that the dispersion flows to a large extent on the elastomer before curing of the elastomer.
• compositions can be applied by any suitable manner such as by brushing, spreading, spraying, rolling, swabbing, gravure, kiss roll, air knife or doctor blade.
• the elastomer in the desired area at least a monomolecular layer thick, preferably a multimolecular layer thick, so long as the layer is not so thick that it flows undesirably.
• the masking material is applied to the section of the silicone elastomer where non-adhesion to the other elastomer layer is desired, leaving substantially the entire length of the perimeter uncoated.
• the entire perimeter does not have to be left uncoated, if there is a portion of the perimeter where non-adherence is desired.
• the coated curable compositions may be cured onto the first layer of elastomer before contacting the second layer of elastomer to the first or the coated curable composition may remain uncured until the two layers of elastomer are cured together while in contact with each other.
• the curable fluorosilicone materials can cure at room temperature, but, typically, the cure is accelerated with heat. If it is desired to cure the coated curable composition before contacting the second layer of elastomer to the first, a suitable low temperature for curing would be about 86°C.; a suitable time for curing would be until the fluorosilicone material is substantially tack-free. Higher temperatures would be suitable, so long as the conditions do not prematurely cure the elastomer layer also. Temperatures above l70°C. would probably be unnecessary as thin layers of the curable fluorosilicone materials cure very quickly at this temperature.
• the second layer of uncured silicone elastomer is placed in contact with the first layer. It is best to apply pressure to the silicone layers where bonding is desired between the two elastomer layers, e.g., at their perimeter.
• the contacting silicone elastomer layers are then cured, preferably under pressure and elevated temperatures.
• a composite is formed having gaps within it where the masking material is present and the elastomers did not bond together.
• two sheets of silicone elastomer are cured while in contact with one another with masking material between them except at their perimeter.
• the elastomer sheets cure or bond together at the perimeter and not at the inner portion of their facing surfaces, thus, forming a fluid-tight reservoir.
• the masking has been described as being placed on one side of an elastomer layer, the masking material can be placed on both sides of an elastomer layer if masking is desired on both sides, especially when more than two layers of elastomer are employed.
• the method of the invention is also useful for forming reservoirs having unusual and/or complex shapes that are not easily constructed using the methods of the prior art. For example, a doughnut-shaped reservoir having a hole in the middle can be made with this method but is not easily made using a mandrel.
• this invention provides a method for blocking the adhesion between layers of silicone elastomer during cure by applying a silicone material which is generally not compatible with the silicone elastomer, such as the fluorosilicone materials described above, between the layers of silicone elastomer before curing.
• the method comprises the steps of a) coating a section of a surface of a first at least partially uncured silicone elastomer body with the masking material, b) placing a second at least partially uncured silicone elastomer body in contact with the surface of the first body, and c) curing the first and second bodies while in contact, whereby the bodies remain unadhered to each other in the area of the coated section, and any uncoated sections of the silicone bodies in contact with each other during cure will bond together.
• Me and Vi denote methyl and vinyl, respectively, temperatures are in degrees Celsius and all parts are by weight, unless otherwise specified.
• This example illustrates the method of making tissue expander envelopes using the present invention and employing curable fluorosilicone compositions.
• the heptane was then removed from the organic phase at a pressure of 150 mm Hg and 40 to 55° and the residue was freed of additional volatile material by heating to 80° at 25 mm Hg vacuum.
• the cohydrolyzate residue was a copolymer of 50 mols of (CF3CF2CF2CF2CH2CH2)(CH3)Si 2/2 siloxane units and 50 mols of (CH3)2SiO 2/2 siloxane units.
• Fluorosilicone Composition "A” was prepared by homogeneously mixing a composition consisting of 10 parts of Fluorosilicone Polymer “A”, 89.6 parts of trichlorotri­fluoroethane, 0.1 parts of methylvinylcyclosiloxane, and 0.3 parts of a complex of divinyltetramethyldisiloxane and H2PtCl6. 0.8 parts Me3SiO(MeHSiO)50SiMe3 was added to 100 parts of Fluorosilicone Composition "A” to make Curable Fluorosilicone Composition "A".
• a sheet of 0.04" thick unvulcanized silicone elastomer consisting essentially of a vinyl-containing dimethylpolysiloxane gum elastomer base, a dimethylmethyl-­hydrogenpolysiloxane cross linker and a platinum catalyst measuring approximately 4 inches wide by 4 inches long was placed onto a compression plate.
• a template for covering about 1/4 inch of the perimeter of the sheet was placed on the top surface of the sheet.
• About 2-3 grams of Curable Fluorosilicone Composition "A" was applied, using a foam swab, to the top surface of the sheet in the area exposed by the template, thereby leaving a perimeter of about 1/4 inch wide around the top surface of the sheet free of coating.
• the template was then removed from the sheet and the coated sheet was placed in an oven heated to about 320°F. for about two minutes to cure the coating.
• This example illustrates the method of making tissue expander envelopes using the present invention employing non-curable fluorosilicone compositions.
• a tissue expander envelope was prepared as described in Example 1 except Fluorosilicone Composition "A” was applied on the elastomer sheet rather than Curable Fluorosilicone Composition "A". After the envelope was removed from the compression plates, the envelope was expanded using a hypodermic needle with a syringe filled with air and the two layers of silicone elastomer separated in the area where the Fluorosilicone Composition "A” was applied.
• This example illustrates the method of making tissue expander envelopes of the present invention employing non-curable fluorosilicone compositions wherein the fluoro­silicone polymer is free of curing radicals.

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• 1988
  • 1988-11-14 EP EP88310708A patent/EP0318193A3/fr not_active Withdrawn
  • 1988-11-24 JP JP63294793A patent/JPH01166756A/ja active Pending

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